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This interactive reviewer covers the complete Karyotyping and Chromosomal Abnormalities curriculum from General Biology 1. It's designed to help you memorize and understand complex biological concepts through active learning.

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  • 13 comprehensive modules covering karyotyping, chromosome structure, and chromosomal abnormalities
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Course Information

Lesson 10 details and credits

LESSON 10: KARYOTYPING AND CHROMOSOMAL ABNORMALITIES

Course Details

  • Subject: General Biology 1
  • Term: Term 1, A.Y. 2025-2026
  • School: Augustinian Abbey School
  • Prepared by: Yuan S. Masuda, RCh

What You'll Learn

This lesson covers the study of chromosomes and their abnormalities:

Karyotyping Basics

  • What is a karyotype?
  • Patterns used in karyotyping
  • Chromosome size and structure

Chromosome Structure

  • Changes through cell cycle
  • Centromere positions
  • Banding patterns

Chromosomal Abnormalities

  • Nondisjunction
  • Aneuploidy & Polyploidy
  • Chromosome breakage

Autosomal Disorders

  • Patau, Edwards, Down syndromes
  • Cri-du-chat syndrome
  • Jacobsen syndrome

Sex-Linked Disorders

  • Turner & Klinefelter syndromes
  • Triple X & XYY syndromes
  • Other sex aneuploidies

Sex and Gender

  • Hermaphroditism
  • Intersex conditions
  • SOGIESC concepts

Karyotyping

General Biology 1 | Prepared by: Yuan S. Masuda, RCh | Augustinian Abbey School

Kyle S

Karyotyping

Karyotype

An ordered display of chromosomes, arranged in homologous pairs by size.

Pairs are matched by:

  • Length
  • Centromere position
  • Band patterns
Clinical Application: Karyotyping may be used to detect and diagnose genetic disorders.
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Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What is a karyotype?

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Karyotype

An ordered display of chromosomes, arranged in homologous pairs by size.

What three criteria are used to match chromosome pairs?

Click to flip

Matching Criteria

Chromosome pairs are matched by:

1. Length

2. Centromere position

3. Band patterns

What is karyotyping used for?

Click to flip

Clinical Use

Karyotyping is used to detect and diagnose genetic disorders.

Ready to Test Yourself?

Quick Quiz

1. What is a karyotype?
A. An ordered display of chromosomes arranged by size
B. A random arrangement of chromosomes
C. A display of genes
D. A process of DNA copying
2. What criteria are used to match homologous chromosome pairs?
A. Color only
B. Length, centromere position, and band patterns
C. Width only
D. Band patterns only
3. What is karyotyping used for?
A. To detect and diagnose genetic disorders
B. To cure genetic disorders
C. To sequence DNA
D. To count blood cells

Patterns in Karyotyping

Three Key Patterns

1. Chromatid Size

Chromosomes differ in length and can be arranged from largest to smallest.

2. Banding Pattern

Staining creates distinctive light and dark bands unique to each chromosome.

3. Centromere Positions

The location where sister chromatids are joined varies among chromosomes.

Memory Aid

SBC

Size | Banding | Centromere

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Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What are the three patterns used in karyotyping?

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SBC Patterns

Size - Chromatid size

Banding - Banding pattern

Centromere - Centromere positions

What does chromatid size refer to in karyotyping?

Click to flip

Chromatid Size

Chromosomes differ in length and can be arranged from largest to smallest for identification.

What creates the banding pattern on chromosomes?

Click to flip

Banding Pattern

Staining creates distinctive light and dark bands that are unique to each chromosome.

What varies in centromere positions?

Click to flip

Centromere Positions

The location where sister chromatids are joined varies among chromosomes (metacentric, submetacentric, acrocentric, telocentric).

Ready to Test Yourself?

Quick Quiz

1. What are the three patterns used in karyotyping?
A. Size, Banding, Centromere
B. Color, Size, Shape
C. Length, Width, Height
D. Position, Pattern, Placement
2. What does the "S" in SBC stand for?
A. Shape
B. Size
C. Structure
D. Symmetry
3. What creates the banding pattern on chromosomes?
A. Staining
B. Microscopes
C. Natural chromosome structure
D. Photography

Chromosome Changes Through the Cell Cycle

Chromosome Appearance by Phase

INTERPHASE

  • Chromosomes are longest and thinnest
  • DNA is replicated but chromosomes are not yet condensed
  • Chromatin is loosely packed

PROPHASE

  • Decrease in chromosome length
  • Increase in chromosome thickness
  • Chromosomes begin to condense

METAPHASE

  • Chromosomes are at their thickest and shortest
  • Well spread in the cell
  • Best stage for karyotyping

ANAPHASE

  • Chromosomes are smallest
  • Sister chromatids separate
  • Move toward opposite poles

Karyotyping Timing

Chromosome measurements are generally taken during mitotic metaphase because chromosomes are most visible and condensed.

Demecolcine: A drug that blocks microtubule formation, stopping the mitotic spindle. As a result, chromosomes stay condensed and get stuck in metaphase - perfect for karyotyping!

Memory Aid

IPMA

Interphase - Longest & Thinnest
Prophase - Getting shorter & thicker
Metaphase - Shortest & Thickest (best for karyotyping!)
Anaphase - Smallest

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Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What happens to chromosomes during interphase?

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Longest and Thinnest

During interphase, chromosomes are at their longest and thinnest state.

DNA is replicated but chromosomes are not yet condensed.

What happens during prophase?

Click to flip

Prophase Changes

Decrease in chromosome length

Increase in chromosome thickness

Chromosomes begin to condense

Why is metaphase the best stage for karyotyping?

Click to flip

Metaphase is Optimal

Chromosomes are at their thickest and shortest

They are well spread in the cell and most visible

Measurements are taken during mitotic metaphase

What does demecolcine do?

Click to flip

Demecolcine

Drug that blocks microtubule formation

Stops the mitotic spindle, keeping chromosomes stuck in metaphase

This keeps chromosomes condensed for karyotyping!

What happens during anaphase?

Click to flip

Anaphase

Chromosomes are smallest

Sister chromatids separate and move toward opposite poles

Ready to Test Yourself?

Quick Quiz

1. When are chromosomes at their longest and thinnest?
A. Interphase
B. Prophase
C. Metaphase
D. Anaphase
2. When are chromosomes at their thickest and shortest?
A. Prophase
B. Metaphase
C. Anaphase
D. Interphase
3. Why is metaphase the best stage for karyotyping?
A. Chromosomes are separating
B. DNA replication is occurring
C. Chromosomes are thickest and most visible
D. Chromosomes are longest
4. What does demecolcine do?
A. Enhances spindle formation
B. Blocks microtubule formation to stop spindle
C. Causes chromosomes to separate
D. Replicates DNA

Centromere Positions

Types Based on Centromere Location

TELOCENTRIC

  • Position: Very end
  • P (Short) Arm: None

ACROCENTRIC

  • Position: Near the end
  • P (Short) Arm: Tiny

SUBMETACENTRIC

  • Position: Off-center
  • P (Short) Arm: Shorter than q arm

METACENTRIC

  • Position: Middle
  • P (Short) Arm: Equal to q arm

Chromosome Arms

Chromosomes have two arms separated by the centromere:

  • p arm (petit) = Short arm (above centromere)
  • q arm = Long arm (below centromere)

Memory Aid

TASM

Telocentric - Tip (end)
Acrocentric - Almost end
Submetacentric - Slightly off-center
Metacentric - Middle

p and q notation: p = petit (French for "small"), q = just the next letter after p
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Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What are the four types of centromere positions?

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TASM

Telocentric - At the very end

Acrocentric - Near the end

Submetacentric - Off-center

Metacentric - In the middle

Where is the centromere in a telocentric chromosome?

Click to flip

Telocentric

Centromere is at the very end

P arm: None

Where is the centromere in an acrocentric chromosome?

Click to flip

Acrocentric

Centromere is near the end

P arm: Tiny

Where is the centromere in a submetacentric chromosome?

Click to flip

Submetacentric

Centromere is off-center

P arm: Shorter than q arm

Where is the centromere in a metacentric chromosome?

Click to flip

Metacentric

Centromere is in the middle

P arm: Equal to q arm

What do p and q arms stand for?

Click to flip

p and q Arms

p arm = petit (French for "small") = Short arm

q arm = Long arm (next letter after p)

Ready to Test Yourself?

Quick Quiz

1. Where is the centromere located in a telocentric chromosome?
A. At the very end
B. Near the end
C. Off-center
D. In the middle
2. What does "p arm" mean in chromosomes?
A. Primary arm
C. Posterior arm
B. Pointed arm
D. Short arm (petit)
3. Which type of chromosome has a p arm equal to the q arm?
A. Telocentric
B. Acrocentric
C. Submetacentric
D. Metacentric
4. Which chromosome type has a tiny p arm?
A. Telocentric
B. Acrocentric
C. Submetacentric
D. Metacentric

Banding Patterns

Heterochromatin vs Euchromatin

FeatureHeterochromatinEuchromatin
DNA PackingTightLoose
Giemsa StainDarkLight
Rich InAdenine & Thymine (A, T)Guanine & Cytosine (G, C)
Gene ConcentrationLowHigh
Gene ActivityInactiveActive

Giemsa Stain and G-Banding

Giemsa Stain: Common dye used to colorize chromosomes. Gives chromosomes a striped appearance because it stains regions rich in adenine (A) and thymine (T).

G-Bands:

  • Dark bands: Contain more heterochromatin
  • Light bands: Contain more euchromatin (G and C rich)

Memory Aid

HETERO = TIGHT + DARK

Heterochromatin = Tightly packed, Dark stain
Euchromatin = Expanded (loose), Light stain

Why the difference? AT-rich regions (heterochromatin) stain darker with Giemsa because of their DNA composition. GC-rich regions (euchromatin) stain lighter.
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Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What stains dark with Giemsa?

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Heterochromatin

Heterochromatin stains dark with Giemsa

It is tightly packed and AT-rich

What stains light with Giemsa?

Click to flip

Euchromatin

Euchromatin stains light with Giemsa

It is loosely packed and GC-rich

What is heterochromatin rich in?

Click to flip

AT-Rich

Heterochromatin is rich in Adenine and Thymine (A, T)

Tightly packed, low gene concentration, inactive

What is euchromatin rich in?

Click to flip

GC-Rich

Euchromatin is rich in Guanine and Cytosine (G, C)

Loosely packed, high gene concentration, active

What is Giemsa stain used for?

Click to flip

Giemsa Stain

Common dye that gives chromosomes a striped appearance

Stains AT-rich regions dark (heterochromatin)

Creates G-banding patterns for chromosome identification

Ready to Test Yourself?

Quick Quiz

1. Which type of chromatin stains dark with Giemsa?
A. Euchromatin
B. Heterochromatin
C. Double helix
D. All chromatin
2. What is heterochromatin rich in?
A. Adenine and Thymine (A, T)
B. Guanine and Cytosine (G, C)
C. All four bases equally
D. Adenine and Uracil
3. Which chromatin type is gene-rich and active?
A. Heterochromatin
B. Euchromatin
C. Both equally
D. Neither - genes are elsewhere
4. What is the DNA packing of heterochromatin?
A. Loose
B. Tight
C. Unwound
D. Not packed

Chromosomal Abnormalities

Types of Chromosomal Abnormalities

Nondisjunction

Normally, meiosis splits chromosomes evenly, but sometimes nondisjunction occurs - chromosomes do not separate properly.

  • Meiosis I: Homologs do not separate
  • Meiosis II: Sister chromatids do not separate

Causes one gamete to get two copies of a chromosome and another to get none.

Aneuploidy

Zygote possesses the wrong number of chromosomes; occurs 10-25% of the time.

  • MONOSOMY: One missing (2n - 1)
  • TRISOMY: One extra (2n + 1)

This error spreads in mitosis and can cause disorders or pregnancy loss.

Polyploidy

Having more than 2 full sets of chromosomes.

  • TRIPLOIDY (3n): From fertilizing an abnormal diploid egg
  • TETRAPLOIDY (4n): From a zygote failing to divide after copying DNA

Common in plants: Bananas (3n), wheat (6n), strawberries (8n)

Polyploid animals: Rare, but exist (some fish and amphibians)

Important: Aneuploidy (extra/missing ONE chromosome) is usually MORE harmful than polyploidy (extra WHOLE sets).

Chromosome Breakage

From meiosis errors or radiation can cause structural changes.

  • Deletions and duplications: Often happen during unequal crossing over in meiosis
  • Large deletions: Can be lethal, especially if key genes are missing
  • Translocations and inversions: Keep all genes but may change gene expression

Memory Aid

NAP

Nondisjunction - doesn't separate
Aneuploidy - wrong number (+/- one)
Polyploidy - extra whole SETS

?

Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What is nondisjunction?

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Nondisjunction

When chromosomes do not separate properly during meiosis.

Results in gametes with too many or too few chromosomes.

What is aneuploidy?

Click to flip

Aneuploidy

Wrong number of chromosomes - extra or missing ONE chromosome.

Monosomy: 2n - 1 (one missing)

Trisomy: 2n + 1 (one extra)

What is polyploidy?

Click to flip

Polyploidy

Having more than 2 full sets of chromosomes.

Triploidy (3n) - 3 sets

Tetraploidy (4n) - 4 sets

Common in plants, rare in animals!

Which is more harmful: aneuploidy or polyploidy?

Click to flip

Aneuploidy

Aneuploidy (missing/extra one chromosome) is usually MORE harmful than polyploidy (extra whole sets).

What can cause chromosome breakage?

Click to flip

Causes of Breakage

Meiosis errors or radiation

Can cause deletions, duplications, translocations, and inversions.

Autosomal Trisomy Disorders

Patau Syndrome (Trisomy 13)

Extra chromosome 13

  • Severe intellectual disability
  • Cleft lip/palate, small head (microcephaly), extra fingers or toes (polydactyly)
  • Heart defects, eye abnormalities, brain malformations
  • Most infants do not survive past first few weeks or months
  • Risk increases with maternal age

Edwards Syndrome (Trisomy 18)

Extra chromosome 18

  • Severe developmental delays
  • Small head, clenched fists with overlapping fingers, rocker-bottom feet
  • Heart defects, kidney problems, growth issues
  • Most infants die before or shortly after birth
  • Only ~10% survive past first year

Down Syndrome (Trisomy 21)

Extra chromosome 21

  • Distinct facial features, short height, heart defects, developmental delays
  • Higher risk of leukemia and Alzheimer's
  • Lower risk of high blood pressure, stroke, and tumors
  • Risk increases with maternal age
  • Most common trisomy that survives to birth
Remember: Of the three autosomal trisomies, Down Syndrome (Trisomy 21) has the highest survival rate and is the most common.

Comparison of Autosomal Trisomies

SyndromeChromosomeSurvivalKey Features
PatauTrisomy 13Lowest - weeks/monthsSevere defects, polydactyly
EdwardsTrisomy 18Very low - ~10% past 1 yearClenched fists, rocker-bottom feet
DownTrisomy 21Highest - can live to adulthoodDistinct features, heart defects

Memory Aid

PED

Patau (13) - Poor survival (worst)
Edwards (18) - Extra low survival
Down (21) - Develops, survives longest

?

Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

Which chromosome is affected in Patau syndrome?

Click to flip

Chromosome 13

Patau syndrome is caused by trisomy 13 (three copies of chromosome 13).

Severe defects, most die within weeks/months.

Which chromosome is affected in Edwards syndrome?

Click to flip

Chromosome 18

Edwards syndrome is caused by trisomy 18.

Clenched fists, rocker-bottom feet, ~10% survive past 1 year.

Which chromosome is affected in Down syndrome?

Click to flip

Chromosome 21

Down syndrome is caused by trisomy 21.

Most common, highest survival rate, can live to adulthood.

Which autosomal trisomy has the highest survival rate?

Click to flip

Down Syndrome (Trisomy 21)

Down syndrome has the highest survival rate among autosomal trisomies.

Many survive to adulthood with proper care.

Ready to Test Yourself?

Quick Quiz

1. Which chromosome is affected in Patau syndrome?
A. Chromosome 18
B. Chromosome 13
C. Chromosome 21
D. Chromosome 5
2. Which autosomal trisomy has the HIGHEST survival rate?
A. Patau syndrome
B. Edwards syndrome
C. Down syndrome
D. All are equally severe
3. What is a characteristic feature of Edwards syndrome?
A. Polydactyly
B. Clenched fists with overlapping fingers
C. Cat-like cry
D. Webbed neck
4. How does maternal age affect trisomy risk?
A. Risk increases with age
B. Risk decreases with age
C. Risk stays the same
D. Only paternal age matters
⏮ THROWBACK (from: Chromosomal Abnormalities)
5. What is aneuploidy?
A. Extra sets of chromosomes
B. Wrong number of chromosomes (+/- one)
C. Chromosome deletion
D. Normal chromosome number

Deletion Syndromes

Cri-du-chat Syndrome

"Cry of the Cat" (French)

A deletion disorder caused by missing part of chromosome 5.

  • Deletion: On the short arm of chromosome 5 (5p deletion)
  • High-pitched, cat-like cry in infants
  • Low birth weight, small head, wide-set eyes, round face
  • Severe developmental delays and intellectual disability
  • Delayed speech and motor skill difficulties
Name Origin: The name comes from the cat-like cry affected infants make due to larynx and nervous system issues.

Jacobsen Syndrome

11q Deletion

A deletion disorder caused by missing part of chromosome 11.

  • Deletion: On the long arm of chromosome 11 (11q deletion)
  • Developmental delays and intellectual disability
  • Distinct facial features: wide-set eyes, small lower jaw, thin upper lip
  • Paris-Trousseau Syndrome: Bleeding disorder (also associated with 11q deletion)
  • Heart defects, growth delays, sometimes hearing loss
  • Behavioral issues (ADHD, autism-like traits)

Comparison of Deletion Syndromes

SyndromeDeletionKey FeatureOther Symptoms
Cri-du-chat5p deletionCat-like cryDevelopmental delays, small head
Jacobsen11q deletionBleeding disorderHeart defects, behavioral issues

Deletion vs Trisomy

Trisomy = Extra chromosome (too much genetic material)

Deletion = Missing part of chromosome (too little genetic material)

Both can cause significant developmental and physical abnormalities.

Memory Aid

5-11

5p deletion = Cri-du-chat (cat cry)
11q deletion = Jacobsen (bleeding)

?

Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What chromosome is affected in Cri-du-chat syndrome?

Click to flip

Chromosome 5

Cri-du-chat is caused by deletion on the short arm of chromosome 5 (5p deletion).

Name means "cry of the cat" in French.

What chromosome is affected in Jacobsen syndrome?

Click to flip

Chromosome 11

Jacobsen syndrome is caused by deletion on the long arm of chromosome 11 (11q deletion).

Associated with Paris-Trousseau bleeding disorder.

What does Cri-du-chat mean in English?

Click to flip

"Cry of the Cat"

From French: "Cri-du-chat"

Infants have a high-pitched, cat-like cry due to larynx and nervous system issues.

What is the difference between deletion and trisomy?

Click to flip

Amount of Genetic Material

Deletion: Missing genetic material (too little)

Trisomy: Extra genetic material (too much)

Both types of abnormalities cause disorders.

Ready to Test Yourself?

Quick Quiz

1. What chromosome is affected in Cri-du-chat syndrome?
A. Chromosome 11
B. Chromosome 5
C. Chromosome 21
D. Chromosome 13
2. What does "Cri-du-chat" mean in English?
A. "Cry of pain"
B. "Cry of the cat"
C. "Happy child"
D. "Missing piece"
3. What chromosome is affected in Jacobsen syndrome?
A. Chromosome 5
B. Chromosome 11
C. Chromosome 18
D. X chromosome
4. What is a key feature of Jacobsen syndrome?
A. Cat-like cry
B. Bleeding disorder (Paris-Trousseau)
C. Extra fingers/toes
D. Webbed neck
⏮ THROWBACK (from: Autosomal Trisomy Disorders)
5. What is the difference between deletion and trisomy?
A. Deletion is missing, trisomy is extra
B. Deletion is extra, trisomy is missing
C. No difference
D. Both add genetic material

Sex-Linked Abnormalities

Turner Syndrome (45,X)

Monosomy in females - Only one X chromosome

  • Short stature
  • Webbed neck, low-set ears, broad chest
  • Ovarian failure → infertility and delayed/absent puberty
  • Heart and kidney defects
  • Possible learning difficulties
  • Not usually inherited - random error during meiosis

Klinefelter Syndrome (47,XXY)

Trisomy in males - Extra X chromosome

  • Tall height, long legs, short torso
  • Small testes, low testosterone, infertility
  • Reduced facial/body hair, possible breast development (gynecomastia)
  • Possible learning difficulties in language and reading
  • May be quiet or shy with lower muscle tone
  • Usually not inherited

Triple X Syndrome (47,XXX)

Trisomy disorder in females - Three X chromosomes

  • Often no visible symptoms
  • Taller than average height
  • May have delayed speech, learning difficulties, or developmental delays
  • Usually normal sexual development and fertility
  • Some may have mild emotional or behavioral issues

XYY Syndrome (47,XYY)

Trisomy disorder in males - Extra Y chromosome

  • Taller than average height
  • Severe cystic acne
  • Macrodontia - larger teeth/teeth gigantism
  • May have mild learning or speech delays
  • Delayed puberty but usually normal sexual development and fertility
  • Not associated with aggression, despite outdated myths

Comparison of Sex-Linked Abnormalities

SyndromeKaryotypeSexKey Features
Turner45,XFemaleMonosomy X, short stature, webbed neck
Klinefelter47,XXYMaleExtra X, tall, infertile
Triple X47,XXXFemaleExtra X, often no symptoms
XYY47,XYYMaleExtra Y, tall, acne

Memory Aid

TK3X

Turner = 45,X (missing one)
Klinefelter = 47,XXY (male with extra X)
3X = 47,XXX (female with extra X)
XYY = 47,XYY (male with extra Y)

?

Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What karyotype does Turner syndrome have?

Click to flip

45,X

Turner syndrome = 45,X (monosomy X)

Females with only one X chromosome.

What karyotype does Klinefelter syndrome have?

Click to flip

47,XXY

Klinefelter syndrome = 47,XXY

Males with an extra X chromosome.

Is XYY syndrome associated with aggression?

Click to flip

No!

XYY is NOT associated with aggression, despite outdated myths.

Key features: tall stature, severe acne, macrodontia.

What sex chromosome abnormality causes short stature?

Click to flip

Turner Syndrome (45,X)

Turner syndrome causes short stature.

Other features: webbed neck, low-set ears, broad chest, infertility.

Ready to Test Yourself?

Quick Quiz

1. What karyotype does Turner syndrome have?
A. 46,XX
B. 45,X
C. 47,XXY
D. 47,XYY
2. What karyotype does Klinefelter syndrome have?
A. 45,X
B. 47,XXY
C. 46,XY
D. 47,XXX
3. Which sex chromosome abnormality causes infertility in males?
A. Triple X syndrome
B. XYY syndrome
C. Klinefelter syndrome
D. Turner syndrome
4. Is XYY syndrome associated with aggressive behavior?
A. No, that is a myth
B. Yes, highly aggressive
C. Yes, moderately aggressive
D. Sometimes
⏮ THROWBACK (from: Deletion Syndromes)
5. What chromosome is affected in Cri-du-chat syndrome?
A. Chromosome 11
B. Chromosome 5
C. Chromosome 13
D. Chromosome 21

Other Sex Chromosome Aneuploidies

Rare Sex Chromosome Variations

Beyond the Common Four

In addition to Turner (45,X), Klinefelter (47,XXY), Triple X (47,XXX), and XYY (47,XYY), there are many other sex chromosome aneuploidies.

List of Sex Chromosome Aneuploidies

XXYY Syndrome

48,XXYY

Males with two X and two Y chromosomes

XXXY Syndrome

48,XXXY

Males with two X and one Y chromosome

XXXYY Syndrome

49,XXXYY

Males with three X and two Y chromosomes

XXXXY Syndrome

49,XXXXY

Males with four X and one Y chromosome

Tetrasomy X

48,XXXX

Females with four X chromosomes

Pentasomy X

49,XXXXX

Females with five X chromosomes

XYYY Syndrome

48,XYYY

Males with one X and three Y chromosomes

XYYYY Syndrome

49,XYYYY

Males with one X and four Y chromosomes

General Pattern: More sex chromosome abnormalities generally lead to more severe symptoms and greater intellectual disability.

Mosaicism

Some individuals have mosaic karyotypes - some cells have the abnormal chromosome number while others are normal. This can result in milder symptoms.

?

Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What is XXYY syndrome?

Click to flip

48,XXYY

Males with two X and two Y chromosomes.

One of the rare sex chromosome aneuploidies.

What is Tetrasomy X?

Click to flip

48,XXXX

Females with four X chromosomes.

Rare condition with more severe symptoms than Triple X.

What generally happens with more sex chromosome abnormalities?

Click to flip

More Severe Symptoms

More abnormalities generally lead to more severe symptoms and greater intellectual disability.

Ready to Test Yourself?

Quick Quiz

1. What is XXYY syndrome?
A. Normal male karyotype
B. Males with two X and two Y chromosomes
C. Normal female karyotype
D. Males with one extra X chromosome
2. What is Tetrasomy X?
A. 47,XXX
B. 48,XXXX
C. 49,XXXXX
D. 48,XXYY
3. What is mosaicism?
B. Some cells abnormal, some normal
A. A type of chromosomal disorder
C. All cells have the same abnormality
D. Two different fertilized eggs fuse
4. What generally correlates with symptom severity in sex chromosome aneuploidies?
B. Number of chromosome abnormalities
A. Age of diagnosis
C. Gender of the individual
D. Height of the individual
⏮ THROWBACK (from: Sex-Linked Abnormalities)
5. What karyotype does Klinefelter syndrome have?
A. 45,X
B. 47,XXY
C. 47,XXX
D. 47,XYY

Hermaphroditism

True Hermaphroditism

True Hermaphroditism

Characterized by the development of ovarian and testicular tissue in the same individual.

  • Most frequent karyotype: 46,XX
  • Very rare in humans

Hermaphrodite vs Intersex

Hermaphrodite

Refers to an organism (common in some animals) that has fully functioning male and female reproductive organs.

  • NOT commonly used for humans - considered misleading and offensive
  • Proper term for humans: Intersex

Hermaphroditism in the Animal Kingdom

Simultaneous Hermaphrodites

Both sexes at the same time

  • Earthworms - exchange sperm during mating
  • Snails - many can self-fertilize or mate with any other snail
  • Leeches

Sequential Hermaphrodites

Change sex during life

  • Protandry: Born male, dominant ones become female
  • Clownfish, Wrasses, Groupers, Parrotfish
  • Protogyny: Born female, later become male

Hermaphroditism in the Plant Kingdom

Perfect (Bisexual) Flowers

Both male and female organs in the same flower

  • Examples: Rose, Lily, Hibiscus, Tomato

Monoecious Plants

Male and female flowers on the same plant, but separate flowers

  • Examples: Corn (maize), Squash, Cucumber

Dioecious Plants

Male and female flowers on separate plants

  • Examples: Date palm, Spinach, Papaya, Kiwi, Holly
Remember: "Perfect" flowers have BOTH male (stamen) and female (pistil) parts. "Monoecious" plants have separate male and female flowers but on ONE plant.
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Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What is true hermaphroditism?

Click to flip

True Hermaphroditism

Development of both ovarian and testicular tissue in the same individual.

Most frequent karyotype: 46,XX

What is the proper term for humans instead of hermaphrodite?

Click to flip

Intersex

The proper term for humans is Intersex, not hermaphrodite.

Hermaphrodite is considered misleading and offensive for humans.

What is a simultaneous hermaphrodite?

Click to flip

Both Sexes at Same Time

Organisms with both male and female organs functioning simultaneously.

Examples: Earthworms, Snails, Leeches

What is a sequential hermaphrodite?

Click to flip

Changes Sex During Life

Organisms that change from one sex to another during their lifespan.

Protandry: male → female | Protogyny: female → male

Examples: Clownfish, Wrasses, Groupers, Parrotfish

Ready to Test Yourself?

Quick Quiz

1. What is the most common karyotype in true hermaphroditism?
A. 46,XY
B. 46,XX
C. 47,XXY
D. 45,X
2. What is the proper term for humans instead of hermaphrodite?
A. Hermaphrodite
B. Intersex
C. Androgynous
D. Bisexual
3. What are simultaneous hermaphrodites?
A. Change sex during life
B. Have both sexes at the same time
C. Are separate male/female organisms
D. Reproduce asexually
4. What is protandry?
A. Born male, become female
B. Born female, become male
C. Has both sexes at once
D. Separate male and female flowers
⏮ THROWBACK (from: Other Sex Aneuploidies)
5. What is Tetrasomy X?
A. 47,XXX
B. 48,XXXX
C. 49,XXXXX
D. 48,XXYY

Intersex Conditions

De La Chapelle Syndrome (46,XX)

Two X chromosomes but develops as male

Due to the presence of the SRY gene on the X chromosome

  • Sex-Determining Region Y (SRY): Gene on Y chromosome that triggers male development
  • During sperm formation, SRY gene accidentally moves from Y to X chromosome
  • Male appearance and external genitalia
  • Small testes and infertility (no sperm production)
  • Low testosterone, delayed puberty, reduced facial/body hair
  • Usually normal intelligence and male gender identity

Swyer Syndrome (46,XY)

XY chromosomes but develops as female

Due to deletion of the SRY gene causing failure to initiate male development

  • Female external genitalia and internal reproductive structures
  • Nonfunctional streak gonads
  • Lack of spontaneous puberty
  • No menstruation
  • Underdeveloped secondary sex characteristics
  • Infertile, but can carry pregnancy with donor eggs and hormone therapy

Comparison of Intersex Conditions

ConditionKaryotypePhenotypeCause
De La Chapelle46,XXMaleSRY gene on X chromosome
Swyer46,XYFemaleSRY gene deleted/mutated
SRY Gene Key: The Sex-Determining Region Y gene is the "master switch" for male development. When it's present → male. When it's absent/mutated → female development.
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Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What karyotype does De La Chapelle syndrome have?

Click to flip

46,XX

De La Chapelle = 46,XX but develops as male.

Caused by SRY gene moving from Y to X chromosome.

What karyotype does Swyer syndrome have?

Click to flip

46,XY

Swyer = 46,XY but develops as female.

Caused by deletion/mutation of SRY gene.

What does the SRY gene do?

Click to flip

Sex-Determining Region Y

The SRY gene is the "master switch" for male development.

Present → male. Absent/mutated → female.

Why does De La Chapelle syndrome result in male development?

Click to flip

SRY Gene Translocation

The SRY gene moves from Y to X chromosome during sperm formation.

XX individual with SRY gene develops as male.

Ready to Test Yourself?

Quick Quiz

1. What karyotype does De La Chapelle syndrome have?
A. 46,XY
B. 46,XX
C. 45,X
D. 47,XXY
2. What karyotype does Swyer syndrome have?
A. 46,XX
B. 46,XY
C. 45,X
D. 47,XXY
3. What does the SRY gene do?
A. Determines egg vs sperm production
B. Only controls testosterone
C. Master switch for male development
D. Determines eye color
4. Why does Swyer syndrome result in female development?
A. SRY gene is present
B. SRY gene is deleted/mutated
C. Extra X chromosome
D. Missing X chromosome
⏮ THROWBACK (from: Hermaphroditism)
5. What is the proper term for humans instead of hermaphrodite?
A. Hermaphrodite
B. Intersex
C. Androgynous
D. Bisexual

Sex and Gender

Sex vs Gender

Sex - Biological Classification

  • Based on chromosomes, hormones, and reproductive anatomy
  • Typically categorized as male, female, or intersex
  • Determined at conception or birth

Gender - Social and Psychological Identity

  • Based on roles, behaviors, and cultural expectations
  • Can be male, female, nonbinary, genderqueer, etc.
  • May align with or differ from biological sex
  • Gender identity can be fluid or fixed, and is self-defined

SOGIESC

What is SOGIESC?

Sexual Orientation, Gender Identity and Expression, and Sex Characteristics

A comprehensive framework used to describe the diverse aspects of human sexuality and gender.

The Components:

  • SO - Sexual Orientation (who you're attracted to)
  • GI - Gender Identity (internal sense of self)
  • ES - Gender Expression (how you present yourself)
  • C - Sex Characteristics (biological traits)
Important Note: SOGIESC recognizes that sex and gender are complex, interconnected aspects of human identity that exist on spectrums rather than binary categories.

Understanding the Spectrum

Biological Sex Spectrum

  • Male, Female, Intersex
  • Based on chromosomes, hormones, anatomy
  • Not always binary

Gender Identity Spectrum

  • Cisgender, Transgender, Non-binary
  • Internal sense of self
  • May differ from assigned sex at birth

Gender Expression Spectrum

  • Masculine, Feminine, Androgynous
  • How one presents to society
  • Can vary by context and culture

Sexual Orientation Spectrum

  • Heterosexual, Homosexual, Bisexual, etc.
  • Who you're attracted to
  • Independent of gender identity
?

Test Yourself FIRST

Try to answer BEFORE flipping. These are practice questions, not notes!

What is the difference between sex and gender?

Click to flip

Sex vs Gender

Sex = Biological (chromosomes, hormones, anatomy)

Gender = Social/Psychological (identity, roles, expression)

What does SOGIESC stand for?

Click to flip

SOGIESC

Sexual Orientation

GIender Identity

Expression

Sex Characteristics

What determines biological sex?

Click to flip

Chromosomes, Hormones, Anatomy

Biological sex is determined by chromosomes, hormones, and reproductive anatomy.

Determined at conception or birth.

Can gender differ from biological sex?

Click to flip

Yes!

Gender identity may align with or differ from biological sex.

It is self-defined and can be fluid or fixed.

Ready to Test Yourself?

Quick Quiz

1. What is the difference between sex and gender?
A. Sex is hormones, gender is identity
B. Sex is biological, gender is social/psychological
C. Both are social constructs
D. No difference
2. What does SOGIESC stand for?
A. Sexual Orientation and Gender Identity
B. Sexual Orientation, Gender Identity/Expression, Sex Characteristics
C. Sex and Gender Equality
D. Sexual Orientation, Gender Identity
3. What determines biological sex?
A. Chromosomes, hormones, and anatomy
B. Social and cultural factors
C. Personal preference
D. Upbringing and environment
4. Can gender differ from biological sex?
A. No, they always align
B. Yes, they can differ
C. Only in rare cases
D. They are the same thing
⏮ THROWBACK (from: Intersex Conditions)
5. What karyotype does De La Chapelle syndrome have?
A. 46,XY
B. 46,XX
C. 47,XXY
D. 45,X

The Big Picture: Chromosomal Abnormalities

Connecting everything together

Why Study Karyotyping?

The Clinical Importance

Karyotyping is a powerful diagnostic tool for detecting and diagnosing genetic disorders.

  • Can identify chromosomal abnormalities before birth
  • Helps explain developmental delays or physical abnormalities
  • Guides genetic counseling for families

Types of Chromosomal Abnormalities

Numerical Abnormalities

  • Aneuploidy: Missing or extra chromosomes
  • Polyploidy: Extra sets of chromosomes

Structural Abnormalities

  • Deletions: Missing chromosome segments
  • Duplications: Extra chromosome segments
  • Translocations: Chromosome segments swap places
  • Inversions: Chromosome segments flip orientation

Key Concepts Summary

TopicKey Points
KaryotypingOrdered display of chromosomes by size, centromere position, band patterns
CentromeresTelocentric, Acrocentric, Submetacentric, Metacentric (TASM mnemonic)
Banding PatternsHeterochromatin (dark) vs Euchromatin (light)
NondisjunctionChromosomes fail to separate properly
TrisomiesPatau (13), Edwards (18), Down (21) - extra autosomes (PED mnemonic)
Deletion SyndromesCri-du-chat (5p), Jacobsen (11q)
Sex Chromosome DisordersTurner (45,X), Klinefelter (47,XXY), Triple X (47,XXX), XYY (47,XYY)
Intersex ConditionsDe La Chapelle (46,XX male), Swyer (46,XY female)
Sex vs GenderSex is biological; Gender is social/psychological identity (SOGIESC framework)
Remember: Karyotyping helps us understand human genetic variation and diagnose conditions that can significantly impact health and development.

From Chromosomes to Identity

The Continuum

From microscopic chromosomes to complex aspects of human identity, Lesson 10 explores the full spectrum:

  • Molecular: Chromosomes, genes, banding patterns
  • Cellular: Karyotyping, nondisjunction, aneuploidy
  • Organismal: Syndromes, physical characteristics
  • Identity: Sex, gender, SOGIESC concepts

Review of Key Mnemonics

NAP (Chromosomal Abnormalities)

Nondisjunction, Aneuploidy, Polyploidy

PED (Autosomal Trisomies)

Patau (13), Edwards (18), Down (21)

TK3X (Sex Chromosome Disorders)

Turner, Klinefelter, 3X, XYY

TASM (Centromere Positions)

Telocentric, Acrocentric, Submetacentric, Metacentric